GF07.61-P-3018MIR ME-SFI Safety Fuel Shutoff, Function

GF07.61-P-3018MIR ME-SFI Safety Fuel Shutoff, Function
- refinement package
- as of model year 09


Function requirements for safety fuel shutoff, general points
^ Circuit 87M ON (engine control ON)
^ Engine running

Safety fuel shutoff, general points
To ensure traffic and passenger safety, safety fuel shutoff is applied.

The ME-SFI control unit (N3/10) controls the safety fuel shutoff according to the following sensors and signals:
- Crankshaft Hall sensor (B70), motor speed
- Throttle valve actuator (M16/6), throttle valve position
- Restraint system control unit (N2/7), direct crash signal
- Restraint system control unit, crash signal over the engine compartment CAN (CAN C)

Safety fuel shutoff function sequence
The safety fuel shutoff is activated by the ME-SFI control unit in the following conditions:
^ Mechanical fault in throttle valve actuator function sequence
^ Function sequence for engine speed "TNA" signal missing
^ Crash signal function sequence

Mechanical fault in throttle valve actuator function sequence
When evaluating the throttle valve position, if the ME-SFI control unit detects a mechanical fault in the throttle valve actuator, it limits the engine speed to about 1400 rpm at idle and about 1800 rpm in driving mode, by switching off fuel injection valves (Y62).

ME-SFI control unit detects engine speed through the signal from the crankshaft Hall sensor.

Function sequence for engine speed "TNA" signal missing
If the "TNA" engine speed signal generated by the ME-SFI control unit fails, the fuel pump (M3) is switched off through the fuel pump relay (K40/5kT).

Crash signal function sequence
If the ME-SFI control unit receives a crash signal directly or indirectly over the engine compartment CAN from the restraint systems control unit, it shuts off the fuel pump through the fuel pump relay and briefly actuates the fuel injection valves in order to depressurize the fuel system.